Conventionally, various silane compounds have been used as the silane coupling agent in order to improve adhesiveness on the interface between organic and inorganic materials. In addition, the silane coupling agent is utilized as a surface preparation agent of organic and inorganic materials; and it is known that the silane coupling agent can provide various functions on the surface of the material.
Among them, the fluorine-containing silane coupling agent is used in various fields as agents providing slipperiness, detachability, water repellency, and oil repellency; and particularly the fluorine-containing silane coupling agents containing a perfluoroalkyl group of 8 or more carbon atoms have been utilized (refer Patent Literature 1 (PTL 1) and Patent Literature 2 (PTL 2), for example).
However, in recent years, it has shown that the perfluorooctane sulfonic acid (PFOS) or the perfluorooctanoic acid (PFOA), which has toxicity and high environment-bio accumulation potentials, can be formed by decomposing the compound containing the perfluoroalkyl group of 8 or more carbon atoms. Thus, there is a problem that restriction has been imposed on the usage of these compounds. Therefore, there is a demand for a material, which will not structurally form PFOS or PFOA with high environment-bio accumulation potentials; has the shortest possible perfluoroalkyl group structure of 6 or less carbon atoms, in the market.
Under the above-described circumstance, a silane compound with a short chain length structure, in which the number of carbon atoms of the perfluoroalkyl group is reduced simply, is proposed (refer PTLs 1 and 2, for example). According to this silane compound with the short chain length structure, there is no risk on the environment since PFOS or PFOA is not formed if it is decomposed.
However, in the fluorine-containing silane coupling agent using this silane compound with the simple short chain length structure, there is a problem that one comparable to the above-described conventional fluorine-containing silane coupling agent containing the perfluoroalkyl group of 8 or more carbon atoms cannot be obtained in terms of the properties of slipperiness, detachability, water repellency, and the like.